Block-signal system.



H. W. BALCOIVI.

BLOCK SIGNAL SYSTEM. APPLICATION FILED APR. 3. 1915.

Patented Mar. 20, 1917.

W8 QNN 0% HARRY w. BALCOM, or wonons'rnn, MASSACHUSETTS.

BLOCK-SIGNAL SYSTEM.

Specification of Letters Patent.

Patented Mar. 20, 1917.

Application filed April 3, 1915. Serial No.'18,877.

To all whom it may concern:

Be it known that I, HARRY lV.BALcoM, a citizen of the United States, residing at lVorcester, in the county of Worcester and State of Massachusetts, have invented a new and useful Block-Signal System, of which the following is a specification.

This invention relates to a block signal system of the type in which a safety signal and a danger signal is provided at each end of each block, said signals being controlled by switches actuated by the trolley on entering or leaving the block.

It is the object of my invention to improve and simplify the construction of such signal systems and to this end I have devised a system in which a single line wire is used to connect the signals at opposite ends of the block.

A further feature of my invention relates to the provision of improved devices for maintaining the signals in circuit after the passage of the trolley; and also to devices for preventing a change of signal on accidental interruption of the trolley current.

My invention further relates to ggrtain arrangements and combinations of parts which will be hereinafter described and more particularly pointed out in the appended claim.

The preferred form of my invention is shown in the drawing, in which the apparatus at the opposite ends of a single block is indicated diagrammatically. s

The apparatus indicated in the diagram of station A is designed for operation by the trolley on entering the block in the direction of the arrow a; and the apparatus indicated in the diagram of station B is designed for operation by the trolley on leaving the block. The two setsof apparatus, however, are substantially identical, with the exception that the apparatus B is reversely connected with the trolley-operated switch. e

The apparatus shown at A is controlled by a switch lO'carried by and connected to the trolley wire lV, and normally maintained in neutral position by opposed springs 1111.

As the trolley enters the block in the direction of the arrow a, the switch is moved by the trolley to contact with a terminal 12 adjacent thereto. The terminal 12 is connected through a wire 13, setting magnet 1 1, w1re 10 and resistance 1" to the earth E.

. lVhe'n the switch 10 contacts with the terminal 12, current passes through this circuit, energizing the magnet 14, and moving the magnet armature lG-from the dotted line to the full line position shown at station A, the armature being normally maintained in its dotted line position by a light tension spring 17. This movement of the armature 16 closes a circuit from the trolley wire W through the wire 20, branch wire 21, safety signal G, wire 22, semaphore S, wire 23, holding magnet 24, and wire 25 to the line wire L.

In station B, the circuit is continued from the line wire L, through wire 26, auxiliary holding magnet 27, wire 28, semaphore S, wire 29, danger signal R, wire 30, and resistance r to the earth E. The flow of current through this circuit renders the signals G and R visible and also energizes the magnets 24 and 27. The holding magnet 24; thereafter retains the armature 16 in the full line position shown at station A, and the safety. signal G at the entering station A and the danger .signal R at the distant or exit station B remain lighted until one of the trolley switches is moved toengage one of the release terminals to be described. The auxiliary magnet 27 also acts to supplement the spring 170 in holding the armature 160 in its full line position in station B.

An important function of the magnet 27 is to prevent reversal of the signals if a car enters the block in defiance of the danger signal B. Such a car would throw the switch 100 to close the circuit' through the wire 130 to the setting magnet 140. If the magnet 27 were omitted the magnet 1 10 would move the armature. 160 to break the circuit through the wire 26 and to close the circuit through the holding magnet 240. This action would extinguish the signal It and light the safety signal G. The magnet 2'7, however, prevents such movement of the armature 160 so long as current is flowing through the magnet coils, and thus prevents. reversal of the signals even if the car is sent into the block in defiance of the danger signal.

A circuit-controlling armature 31 normally completes the circuit between the two parts of the wire 22, the armature being held in Operative position by a coil spring 32 and the two parts of the wire being connected by a metallic strip mounted on but insulated from the armature. In a similar manner the armature 16 completes the circuit through the two parts of the wire 25 when in the full line position shown at station A. A third armature 33 normally closes the circuit through the two parts of the wire 29'.

As the trolley leaves the block it engages the trolley switch 100 moving the same to engage the terminal 34 connected to the release wire 40. Current then passes from the trolley wire TV through the trolley switch 100, the wire 40, the release magnet 41, the wire 42, a second release magnet 43, wire 44, and resistance r to the earth E.

The passage of current through the circuit just defined energizes the magnets 41 and 43, the magnet 41 moving the armature 33 to the right and thereby breaking the circuit through the wire 29. The circuit through the signals G and R is thus broken, interrupting the flow of current through the holding magnet 24 and releasing the armature 16, which moves to dotted line position under the influence of the spring 17 and permanently opens the circuit through the two parts of the Wire 25. The circuit thus remains open even after the armature 33 is released and returns to its normal operative position.

Should the car pass out at the rear of the block instead of continuing through the block, the trolley will cause the switch 10 to contact with the release terminal 340, permitting current to flow through the wire 400, release magnet 410, wire .420, release magnet 430, the wire 440, and resistance r to the earth E. The magnet 430 will thus become effective to move the armature 31 to the left, opening the circuit through the wire 22. The effect of this action will be exactly identical with that caused by the actuation-of the armature 33 by the magnet 41, as previously described. The circuit through the wire 22 and consequently through the holding magnet 24 will be broken and the signal circuit will be permanently opened.

Should the car first enter the block in the direction opposite to the arrow a, the switch 100 will be moved to engage the setting terminal 120, thus closing the circuit through the'wire 130, setting magnet 140, the wire 150 and resistance r to the earth E. Current flowing through this circuit will energize the setting magnet 140, moving the armature 160 to the dotted line position shown in the diagram B, thus closing the circuit through the safety signal .Gr', semaphore S holding magnet 240, line L, auxiliary holding magnet 270, semaphore S danger signal R, wire 300, and resistance r to the earth E, substantially as previously de scribed. This circuit through the signals G and R may be broken by the release magnets 43 and 410, according to the direction in which the car leaves-the block, in eX-.

actly the same manner that the circuit through the signals G and R was controlled by the magnets 41 and 430. g

In order that the parts may not change their relative positions in the event of acci dental interruption of the trolley current, I provide in the station A 'a locking lever 50 controlled by a locking magnet 51 connected by a wire 52 and the wire 20 to the trolley W and connected through a wire 53 and resistance 7 to the earth E. The magnet 51 is therefore constantly energized as long as current flows through the trolley W, and the lever 50 is thus normally maintained in the inoperativ position shown in the diagram.

If the trolley current is interrupted the lever 50 will be moved upwardly by the tension spring 54, engaging the end of the armature 16 and retaining it in the position which it previously occupied. Thus if the armature was previously in the full line position of station A with the signals G and R in circuit, it will be prevented from swinging to the right and thus opening the signal circuit. If, however, it were previously in the dotted line position shown at diagram A, it will remain in such position. Exactly similar locking devices are provided in station B. I

The use of the semaphore S, S, S and S is optional and they may be omitted without changing the operation of thejdevice in any way beyond the necessary re adjustment of the resistances.

By the use of the holding magnets 24 and 240, I avoid the use of complicated devices for prolonging the contact of the trolley switch.

Having thus described my invention, it will be evident that changes and modifications can be made therein withoutdeparting from the spirit and scope thereof as set forth in the claim, and I do not wish to be otherwise limited to the details herein disclosed, but what I claim is A block signal system having, in combination, a trolley wire carrying current, a trolley-controlled switch at each end of each block connected to said trolley wire, a safety signal and a danger signal at each station, a single line wire having separate branch connections to each of the four signals, an armature in each station effective in normal inoperative position to close the adjacent danger signal branch circuit-and effective in operative position to close the adjacent safety signal branch circuit, a magnet controlled by said trolley switch effective to move said armature to! operative position, a magnet in said safety signal branch circuit eifective to thereafter hold said armature in operative position until the circuit is broken, and a magnet in said danger signal branch circuit effective to prevent movement of said armature from normal position While said danger signal and the distant safety signal are in operation.

In testimony whereof I have hereunto' set my hand.

HARRY WV. BALGOM.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. G. 

